1. Field of the Invention
The present invention relates to a thin film transistor that may be used in a display device and more particularly to a gate-body contact thin film transistor having a gate electrode connected with an impurity region for a body contact formed in an active layer.
2. Description of the Related Art
A polysilicon thin film transistor used in a flat panel display may be a floating body TFT in which an island-type active layer may be floated. The floating body TFT may have the problem that both the drain current and the saturation region of the drain current may be reduced as the device is miniaturized.
A thin film transistor with a gate-body contact structure to try to solve this issue was discussed in Korean Patent Application No. 2003-056594. The device described in that document may have the advantages that a low voltage drive may be possible and a threshold voltage with a steep slope and a high drain current can be provided by forming a body contact region that may have a conductivity-type opposite to source/drain regions in the active layer and applying the gate voltage.
Such a thin film transistor, however, may require extra wiring for connecting the body contact region and the gate electrode. An extra wiring process may be made before forming the active layer to directly contact a metal connection wiring with an amorphous silicon layer, but this method may have the problem that the active layer may be contaminated by the metal material of the connection wiring.